Drafting-tool.



(LH. ROBINS. DRAFTING TOOL. APPLICATION FILED mm. 17, 1908.

Patented Nov. 10, 1908.

UNITED STATES ATENT OFFICE.

CHARLES H. ROBINS, OF COEUR DALENE, IDAHO.

DRAFTING-TOOL.

T 0 all whom it may concern:

Be it known that I, CHARLES H. ROBINS, a citizen of the United States,residing at Coeur dAlene, in the county of Kootenai and State of Idaho,have invented a new and useful Drafting-Tool, of which the following isa specification.

This invention relates to instruments for measuring and determiningangles.

The invention has especial reference to such instruments for use inconnection with miter boxes for taking angles and indicating the degreeof the bi-secting line of such angle, or the degree on which the mitersaw would be set to cut the oint of such angle.

The invention consists in an improved instrument of this characterconstructed and arranged as herein set forth and claimed.

Referring to the accompanying drawings, in which like parts aredesignated by similar characters, Figure 1 represents an instrumentconstructed in accordance with this invention, shown as set for use inconnection with an ordinary form of protractor. Fig. 2 is a View inelevation and partly broken away of the measuring instrument. Fig. 3

is a view in longitudinal section showing the 7 interior construction ofthe instrument. Fig. i is a detail view in cross section of one end ofthe instrument. Fig. 5 is a diagrammatic view of a miter box baseprovided with a protractor to illustrate the use of the instrument. Fig.6 is a detail view with parts broken away, showing a modification of theinvention.

The measuring instrument is constructed with a handle 1 and a blade 2hinged thereto. The handle is formed of two members 3 and 4, the member3 being preferably solid but may be hollow for the sake of lightness, ifdesired. The member 3 is provided adjacent to one end with a circularrecess 5 and a smaller circular recess 6 communicating with saidcircular recess 5, and in said circular recess 5 is located a dial 7mounted on a shaft 8 having at its rear end a pinion 9, the parts beingheld in recesses by a pin 10 engaging the circular slot 10 in the pin 8.The member 3 is further provided with a circular recess 11 opening intothe recess 6 and in the recess 11 is located a gear wheel 12 engagingand meshing with the pinion 9. The toothed wheel 12 is formed with acircular head 13. Secured on the member 3 by means of screws 14 are twoplates 15 having at their outer ends semi-circular projectionsSpecification of Letters Patent.

Application filed March 17, 1908. Serial No. 421,692.

16 which encircle the head 13 of the toothed wheel 12. The head 13 ofthe toothed wheel 12 is formed with an oblong angular lug 17 and theblade 2 is connected therewith by a 19 having a diagonal edge 20, asshown in Fig.2, against which is adapted to rest the diagonal edge 21 ofthe blade 2 when it is in closed position in the handle. The members 3and a are secured together at their rear end by screws 22 passingthrough the members 3 and at and the plates 19 and 15. In the outer endof the handle is located a screw 23 having its head mounted in acircular recess 24. in the member 4: with the shank of said screwpassing through the lug 17, the toothed wheel 12 and the member 3.

The member 41 is formed with a hollow or cored out recess in whichlocated a rod 26 having a handle 27 at one end and having its forwardend engaging a lug 28 in the member by means of a screw thread. Theblade may be locked in adjusted position by screwing the rod 26, itsouter end impinging against the under side of the head of the screw 23and thereby clamping together the several parts which are mounted on thescrew thread 23.

In Fig. 1 is shown a diagrammatic protractor 29 to illustrate the use ofthe instrument, and in Fig. 5 a miter box 30 and a pro tractor 31 toalso indicate the use of the instrument. By having the blade 2 slotted,as set forth, the blade may be adjusted and moved backwardsand forwardson the lug 17 and may be swung to open or closed position, and when notin use may be closed into the handle with its diagonal end 21 restingagainst the diagonal edge 20 of the plate 19.

To indicate the use of the instrument as shown in Fig. 1, it is set atan angle of 120 which is bisected by the dotted line passing through As60 is 30 from 90 at a right angle, the miter box would set on 30 I tocut molding or other material to make the same number on this angle.This is shown by the dial 7 which in the position shown to which theblade 2 has been moved or set brings the figure 30 opposite theindicating line 32 on the handle. The dial in order to accurately obtainthese measurements is provided on its surface adjacent to its peripherywith numbers from zero to forty-five. It

will thus be seen that to indicate the degree of angle at which moldingshould be cut, the tool should be placed in position in the angle andthe figure 011 the dial will indicate the degree on which to set themiter saw.

The illustration in Fig. 5 indicates the use of a miter box with adiagrammatic protractor numbered by degrees at square cut and marked inopposite directions. Using the instrument with this protractor and themiter box, the degree can be obtained as herein before set forth, onwhich to set the miter saw. By means of this invention the degree onwhich to set the miter box to cut material to fit any angle greater thancan be obtained.

In the modification shown in Fig. 6, two sets of figures from 0 to 15,one for each 90 are arranged on the handle in a circle about the figureson the dial and are for the purpose of indicating the bisecting line ofan angle, when it is not practical to use a miter box, as in framingtimbers, and so forth.

The outside figures on the left of the dial are for use with anglesgreater than right angles, and those on the right for less than rightangles.

The tool is shown as open to the blade being in the position on thediagrannnatic protractor 29 as indicated in Fig. 1, the number indicatedon the dial 7 opposite the figure O in the outside circle of figures,being 30. To bisect the angle, close the blade till the figure 30 on thedial is moved around and is located opposite the 30 in the outsidecircle of figures on the left of the dial. To

bisect any angle move the blade towards the handle, till the figureindicated on the dial is moved opposite the corresponding figure in theoutside circle of figures.

What is claimed is 1. A measuring instrument of the character describedconsisting of a handle formed of two longitudinal plates securedtogether; a gear mechanism located and inclosed within one of saidplates and having a rotary dial located in the face of said plate; apair of longitudinal plates secured to the other side of said plate andcovering said mechanism; and a slotted blade hinged to the handle andgear mechanism and slidably connected with the latter.

2. In a measuring instrument of the class described, a handle memberprovided with a recess at one end, a gear mounted within the recess andhaving on one face a projecting boss, at headed screw extending throughthe handle and on which the gear is free to rotate, an endwise movablelocking member for engaging the head of the screw and clamping the gear,an indicating disk operatively connected to the gear, and a blade havinga longitudinally disposed slot for the reception of said boss.

In testimony that I claim the foregoing as my own, I have hereto atlixedmy signature in the presence of two witnesses.

CHARLES H. ROBINS.

itnesses Isaac THOMPSON, LOUIS OPIER.

